1. Field of the Invention
The invention relates to an electronic key system which checks a key code stored in a lock device that locks an entrance into a predetermined space against a key code stored in an electronic key using two-way communication, and allows an unlocking operation of the lock device if the two codes match. More particularly, the invention relates to an electronic key system that enables only the key code(s) of an additional key(s), from among the registered key codes, to be batch erased.
2. Description of the Related Art
Japanese Patent Application Publication No. JP-A-8-150899, for example, discloses an immobilizer system which is one related security system for a vehicle. This immobilizer system checks the key against a key code using two-way communication with the vehicle, and allows the engine to start only if the key code matches. Vehicles in Europe have been required to be provided with this immobilizer system as standard equipment since 1997, and there is an increasing trend to use them in vehicles in Japan as well.
Japanese Patent Application Publication No. JP-A-2004-314806, for example, discloses a smart start system which is another related technology that has appeared in recent years. This smart start system checks an electronic key against a key code using two-way communication with the vehicle. If the key code matches, the engine is allowed to be started/stopped simply by the push of a push button-type ignition switch as long as the electronic key is somewhere on the user's person, i.e., the engine can be started/stopped without the user having to take the electronic key out of a clothes pocket or the like.
Similarly, Japanese Patent Application Publication No. JP-A-2005-127050 also discloses a smart entry system which checks an electronic key against a key code using two-way communication with the vehicle. If the key code matches, the door lock is unlocked and the door able to be opened by the user simply grabbing (touching) the outside door handle as long as the electronic key is somewhere on the user's person, i.e., the door can be unlocked without the user having to take the electronic key out of a clothes pocket or the like.
A system which integrates these two technologies is referred to, for example, as a smart entry & push button engine start system and is already offered in some vehicles on the market today. With this smart entry & push button engine start system, the key only needs to transmit a key code to the vehicle using two-way communication, as described above, which means the key does not necessarily have to be a mechanical key. Therefore, the key can be incorporated into a mobile phone, a wristwatch or other item usually carried by the user.
Thus, it is conceivable that, in addition to the electronic key (the master key) with a registered key code that was handed over to the user by the manufacturer at the time the vehicle was purchased, the user may also purchase an aftermarket electronic key which is integrated into, for example, a mobile phone or a wristwatch, as described above, to increase mobility and enhance fashion. The key code of that electronic key may be newly registered with the vehicle and the item then used as an additional key.
According to the apparatus disclosed in Japanese Patent Application Publication No. JP-A-8-150899 described above, however, if the driver loses a key, then all of the registered key codes, including that of the lost key, are erased so the key codes of any keys that the driver has at hand must be re-registered.
When this method is applied to recent smart entry & push button engine start systems such as that described above, problems can arise when, for example, the vehicle is sold as a used vehicle to another person.
That is, when a key that is integrated with a mobile phone or a wristwatch is used as an additional key, for example, it is unlikely that a new user that purchased the vehicle as a used vehicle will also receive that mobile phone or wristwatch from previous user. As a result, the vehicle will be transferred from the previous user to the new user while the key codes of these additional keys registered with the vehicle are still valid.
Thus, even after the vehicle is sold, it is still possible for the previous user to open a door of the vehicle that is no longer his or hers and start the engine using the additional key that he or she still has, which is of course undesirable. Because a general user is unable to check the registered key codes, however, a new user is unable to know if any additional keys have been registered unless he or she goes to a specialty store such as a dealer and has a specialist there check the key codes registered with the vehicle.
If an additional key(s) that is registered with the vehicle has not been handed over to the new user, the new user must first have all of the registered key codes erased by the specialist and then have the key at hand registered again.
This kind of inconvenience occurs because, with the method disclosed in Japanese Patent Application Publication No. JP-A-8-150899 described above, it is impossible to identify whether the key code registered with the vehicle is the key code for the master key that has been registered in advance by a vehicle production worker at the time of shipping of the vehicle or a key code for an additional key that was registered after the vehicle was shipped.
In addition, houses which employ a smart entry system such as that described above for the front door are also now appearing. In this case, as well, the same kind of inconvenience when erasing an additional key(s) can also occur.